Having played his last game with the Kookaburras in October 2009, Guest has been troubled with injuries throughout the last 18 months. After injuring ligaments in his hand during last years Australian Hockey League, Guest had ongoing hamstring injuries throughout 2009 which meant he could not compete in the 2009 Champions Trophy in Melbourne. 
Further injuries to his knee meant he was also not in contention for the World Cup played in early 2010. He is currently in Brisbane with the Tassie Tigers competing in the 2010 Australian Hockey League, however he has been unable to play due to injury. Having played 103 international games and scoring 19 goals, Guest said he was content with his career.
“I have no regrets which makes it easier to make the decision to retire. I am proud to have played over 100 games for Australia and seeing as how I first made my way into the national squad in 2005 at the AHL in Brisbane, I thought it was a good time to announce my retirement five years later in Brisbane again,” said Guest.
Guest said winning bronze at the 2008 Beijing Olympics was undoubtedly the highlight of his career.  “That (the Olympics) is what I worked towards my entire hockey career and it was always my goal. I was disappointed not to have played in a World Cup campaign but it was great to have won two Champions Trophy gold medals,” said Guest. 
Guest said he was excited to see the direction that the Kookaburras are heading toward with the London Olympics only two years away.
“We have great depth at the moment which I think is the key to a good brand of hockey. I would like to acknowledge previous coaches Barry Dancer and Colin Batch who I believe began building a good system eight years ago. Now Ric Charlesworth has come in and continued with that and has brought a freshness to the way we play. The hardest part will be when we come to the Olympics and have such a deep squad, it will be hard to pick the side. But that is always a good problem to have,” said Guest.